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  <section id="fortrancinterface">
<span id="module:FortranCInterface"></span><h1>FortranCInterface<a class="headerlink" href="#fortrancinterface" title="Permalink to this heading">¶</a></h1>
<p>Fortran/C Interface Detection</p>
<p>This module automatically detects the API by which C and Fortran
languages interact.</p>
<section id="module-variables">
<h2>Module Variables<a class="headerlink" href="#module-variables" title="Permalink to this heading">¶</a></h2>
<p>Variables that indicate if the mangling is found:</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL_FOUND</span></code></dt><dd><p>Global subroutines and functions.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE_FOUND</span></code></dt><dd><p>Module subroutines and functions (declared by &quot;MODULE PROCEDURE&quot;).</p>
</dd>
</dl>
<p>This module also provides the following variables to specify
the detected mangling, though a typical use case does not need
to reference them and can use the <a class="reference internal" href="#module-functions">Module Functions</a> below.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL_PREFIX</span></code></dt><dd><p>Prefix for a global symbol without an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL_SUFFIX</span></code></dt><dd><p>Suffix for a global symbol without an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL_CASE</span></code></dt><dd><p>The case for a global symbol without an underscore,
either <code class="docutils literal notranslate"><span class="pre">UPPER</span></code> or <code class="docutils literal notranslate"><span class="pre">LOWER</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL__PREFIX</span></code></dt><dd><p>Prefix for a global symbol with an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL__SUFFIX</span></code></dt><dd><p>Suffix for a global symbol with an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_GLOBAL__CASE</span></code></dt><dd><p>The case for a global symbol with an underscore,
either <code class="docutils literal notranslate"><span class="pre">UPPER</span></code> or <code class="docutils literal notranslate"><span class="pre">LOWER</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE_PREFIX</span></code></dt><dd><p>Prefix for a module symbol without an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE_MIDDLE</span></code></dt><dd><p>Middle of a module symbol without an underscore that appears
between the name of the module and the name of the symbol.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE_SUFFIX</span></code></dt><dd><p>Suffix for a module symbol without an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE_CASE</span></code></dt><dd><p>The case for a module symbol without an underscore,
either <code class="docutils literal notranslate"><span class="pre">UPPER</span></code> or <code class="docutils literal notranslate"><span class="pre">LOWER</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE__PREFIX</span></code></dt><dd><p>Prefix for a module symbol with an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE__MIDDLE</span></code></dt><dd><p>Middle of a module symbol with an underscore that appears
between the name of the module and the name of the symbol.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE__SUFFIX</span></code></dt><dd><p>Suffix for a module symbol with an underscore.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FortranCInterface_MODULE__CASE</span></code></dt><dd><p>The case for a module symbol with an underscore,
either <code class="docutils literal notranslate"><span class="pre">UPPER</span></code> or <code class="docutils literal notranslate"><span class="pre">LOWER</span></code>.</p>
</dd>
</dl>
</section>
<section id="module-functions">
<h2>Module Functions<a class="headerlink" href="#module-functions" title="Permalink to this heading">¶</a></h2>
<dl class="cmake command">
<dt class="sig sig-object cmake" id="command:fortrancinterface_header">
<span class="sig-name descname"><span class="pre">FortranCInterface_HEADER</span></span><a class="headerlink" href="#command:fortrancinterface_header" title="Permalink to this definition">¶</a></dt>
<dd><p>The <code class="docutils literal notranslate"><span class="pre">FortranCInterface_HEADER</span></code> function is provided to generate a
C header file containing macros to mangle symbol names:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>FortranCInterface_HEADER(&lt;file&gt;
                         [MACRO_NAMESPACE &lt;macro-ns&gt;]
                         [SYMBOL_NAMESPACE &lt;ns&gt;]
                         [SYMBOLS [&lt;module&gt;:]&lt;function&gt; ...])
</pre></div>
</div>
<p>It generates in <code class="docutils literal notranslate"><span class="pre">&lt;file&gt;</span></code> definitions of the following macros:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>#define FortranCInterface_GLOBAL (name,NAME) ...
#define FortranCInterface_GLOBAL_(name,NAME) ...
#define FortranCInterface_MODULE (mod,name, MOD,NAME) ...
#define FortranCInterface_MODULE_(mod,name, MOD,NAME) ...
</pre></div>
</div>
<p>These macros mangle four categories of Fortran symbols, respectively:</p>
<ul class="simple">
<li><p>Global symbols without '_': <code class="docutils literal notranslate"><span class="pre">call</span> <span class="pre">mysub()</span></code></p></li>
<li><p>Global symbols with '_'   : <code class="docutils literal notranslate"><span class="pre">call</span> <span class="pre">my_sub()</span></code></p></li>
<li><p>Module symbols without '_': <code class="docutils literal notranslate"><span class="pre">use</span> <span class="pre">mymod;</span> <span class="pre">call</span> <span class="pre">mysub()</span></code></p></li>
<li><p>Module symbols with '_'   : <code class="docutils literal notranslate"><span class="pre">use</span> <span class="pre">mymod;</span> <span class="pre">call</span> <span class="pre">my_sub()</span></code></p></li>
</ul>
<p>If mangling for a category is not known, its macro is left undefined.
All macros require raw names in both lower case and upper case.</p>
<p>The options are:</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">MACRO_NAMESPACE</span></code></dt><dd><p>Replace the default <code class="docutils literal notranslate"><span class="pre">FortranCInterface_</span></code> prefix with a given
namespace <code class="docutils literal notranslate"><span class="pre">&lt;macro-ns&gt;</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">SYMBOLS</span></code></dt><dd><p>List symbols to mangle automatically with C preprocessor definitions:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>&lt;function&gt;          ==&gt; #define &lt;ns&gt;&lt;function&gt; ...
&lt;module&gt;:&lt;function&gt; ==&gt; #define &lt;ns&gt;&lt;module&gt;_&lt;function&gt; ...
</pre></div>
</div>
<p>If the mangling for some symbol is not known then no preprocessor
definition is created, and a warning is displayed.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">SYMBOL_NAMESPACE</span></code></dt><dd><p>Prefix all preprocessor definitions generated by the <code class="docutils literal notranslate"><span class="pre">SYMBOLS</span></code>
option with a given namespace <code class="docutils literal notranslate"><span class="pre">&lt;ns&gt;</span></code>.</p>
</dd>
</dl>
</dd></dl>

<dl class="cmake command">
<dt class="sig sig-object cmake" id="command:fortrancinterface_verify">
<span class="sig-name descname"><span class="pre">FortranCInterface_VERIFY</span></span><a class="headerlink" href="#command:fortrancinterface_verify" title="Permalink to this definition">¶</a></dt>
<dd><p>The <code class="docutils literal notranslate"><span class="pre">FortranCInterface_VERIFY</span></code> function is provided to verify
that the Fortran and C/C++ compilers work together:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>FortranCInterface_VERIFY([CXX] [QUIET])
</pre></div>
</div>
<p>It tests whether a simple test executable using Fortran and C (and C++
when the CXX option is given) compiles and links successfully.  The
result is stored in the cache entry <code class="docutils literal notranslate"><span class="pre">FortranCInterface_VERIFIED_C</span></code>
(or <code class="docutils literal notranslate"><span class="pre">FortranCInterface_VERIFIED_CXX</span></code> if <code class="docutils literal notranslate"><span class="pre">CXX</span></code> is given) as a boolean.
If the check fails and <code class="docutils literal notranslate"><span class="pre">QUIET</span></code> is not given the function terminates with a
fatal error message describing the problem.  The purpose of this check
is to stop a build early for incompatible compiler combinations.  The
test is built in the <code class="docutils literal notranslate"><span class="pre">Release</span></code> configuration.</p>
</dd></dl>

</section>
<section id="example-usage">
<h2>Example Usage<a class="headerlink" href="#example-usage" title="Permalink to this heading">¶</a></h2>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">include(</span><span class="nb">FortranCInterface</span><span class="nf">)</span>
<span class="nf">FortranCInterface_HEADER(</span><span class="nb">FC.h</span><span class="w"> </span><span class="no">MACRO_NAMESPACE</span><span class="w"> </span><span class="s">&quot;FC_&quot;</span><span class="nf">)</span>
</pre></div>
</div>
<p>This creates a &quot;FC.h&quot; header that defines mangling macros <code class="docutils literal notranslate"><span class="pre">FC_GLOBAL()</span></code>,
<code class="docutils literal notranslate"><span class="pre">FC_GLOBAL_()</span></code>, <code class="docutils literal notranslate"><span class="pre">FC_MODULE()</span></code>, and <code class="docutils literal notranslate"><span class="pre">FC_MODULE_()</span></code>.</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">include(</span><span class="nb">FortranCInterface</span><span class="nf">)</span>
<span class="nf">FortranCInterface_HEADER(</span><span class="nb">FCMangle.h</span>
<span class="w">                         </span><span class="no">MACRO_NAMESPACE</span><span class="w"> </span><span class="s">&quot;FC_&quot;</span>
<span class="w">                         </span><span class="no">SYMBOL_NAMESPACE</span><span class="w"> </span><span class="s">&quot;FC_&quot;</span>
<span class="w">                         </span><span class="no">SYMBOLS</span><span class="w"> </span><span class="nb">mysub</span><span class="w"> </span><span class="nb">mymod</span><span class="o">:</span><span class="nb">my_sub</span><span class="nf">)</span>
</pre></div>
</div>
<p>This creates a &quot;FCMangle.h&quot; header that defines the same <code class="docutils literal notranslate"><span class="pre">FC_*()</span></code>
mangling macros as the previous example plus preprocessor symbols
<code class="docutils literal notranslate"><span class="pre">FC_mysub</span></code> and <code class="docutils literal notranslate"><span class="pre">FC_mymod_my_sub</span></code>.</p>
</section>
<section id="additional-manglings">
<h2>Additional Manglings<a class="headerlink" href="#additional-manglings" title="Permalink to this heading">¶</a></h2>
<p>FortranCInterface is aware of possible <code class="docutils literal notranslate"><span class="pre">GLOBAL</span></code> and <code class="docutils literal notranslate"><span class="pre">MODULE</span></code> manglings
for many Fortran compilers, but it also provides an interface to specify
new possible manglings.  Set the variables:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>FortranCInterface_GLOBAL_SYMBOLS
FortranCInterface_MODULE_SYMBOLS
</pre></div>
</div>
<p>before including FortranCInterface to specify manglings of the symbols
<code class="docutils literal notranslate"><span class="pre">MySub</span></code>, <code class="docutils literal notranslate"><span class="pre">My_Sub</span></code>, <code class="docutils literal notranslate"><span class="pre">MyModule:MySub</span></code>, and <code class="docutils literal notranslate"><span class="pre">My_Module:My_Sub</span></code>.
For example, the code:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">set(</span><span class="nb">FortranCInterface_GLOBAL_SYMBOLS</span><span class="w"> </span><span class="nb">mysub_</span><span class="w"> </span><span class="nb">my_sub__</span><span class="w"> </span><span class="no">MYSUB_</span><span class="nf">)</span>
<span class="w">  </span><span class="c">#                                  ^^^^^  ^^^^^^   ^^^^^</span>
<span class="nf">set(</span><span class="nb">FortranCInterface_MODULE_SYMBOLS</span>
<span class="w">    </span><span class="nb">__mymodule_MOD_mysub</span><span class="w"> </span><span class="nb">__my_module_MOD_my_sub</span><span class="nf">)</span>
<span class="w">  </span><span class="c">#   ^^^^^^^^     ^^^^^   ^^^^^^^^^     ^^^^^^</span>
<span class="nf">include(</span><span class="nb">FortranCInterface</span><span class="nf">)</span>
</pre></div>
</div>
<p>tells FortranCInterface to try given <code class="docutils literal notranslate"><span class="pre">GLOBAL</span></code> and <code class="docutils literal notranslate"><span class="pre">MODULE</span></code> manglings.
(The carets point at raw symbol names for clarity in this example but
are not needed.)</p>
</section>
</section>


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<li><a class="reference internal" href="#">FortranCInterface</a><ul>
<li><a class="reference internal" href="#module-variables">Module Variables</a></li>
<li><a class="reference internal" href="#module-functions">Module Functions</a></li>
<li><a class="reference internal" href="#example-usage">Example Usage</a></li>
<li><a class="reference internal" href="#additional-manglings">Additional Manglings</a></li>
</ul>
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